Interpreting methane variations in the past two decades  using measurements of CH&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt; mixing ratio and isotopic composition

Monteil, Guillaume; Houweling, Sander; Dlugockenky, E.J.; Janssens-Maenhout, Greet; Vaughn, Bruce H.; White, James W. C.; Röckmann, T.

doi:10.5194/acp-11-9141-2011

Cited by 107 publications

(115 citation statements)

References 53 publications

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“…Generally, the isotope signal of CH 4 from wetlands appears to be rather constant and sufficiently distinct from other large sources, e.g. biomass burning (Monteil et al, 2011), supporting the use of isotopes to better constrain sources and sinks of atmospheric CH 4 by inverse modelling.…”

Section: Discussionmentioning

confidence: 99%

Methane dynamics in the subarctic tundra: combining stable isotope analyses, plot- and ecosystem-scale flux measurements

et al. 2016

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Abstract. Methane (CH 4 ) fluxes were investigated in a subarctic Russian tundra site in a multi-approach study combining plot-scale data, ecosystem-scale eddy covariance (EC) measurements, and a fine-resolution land cover classification scheme for regional upscaling. The flux data as measured by the two independent techniques resulted in a seasonal (May-October 2008) cumulative CH 4 emission of 2.4 (EC) and 3.7 g CH 4 m −2 (manual chambers) for the source area representative of the footprint of the EC instruments. Upon upscaling for the entire study region of 98.6 km 2 , the chamber measured flux data yielded a regional flux estimate of 6.7 g CH 4 m −2 yr −1 . Our upscaling efforts accounted for the large spatial variability in the distribution of the various land cover types (LCTs) predominant at our study site. Wetlands with emissions ranging from 34 to 53 g CH 4 m −2 yr −1 were the most dominant CH 4 -emitting surfaces. Emissions from thermokarst lakes were an order of magnitude lower, while the rest of the landscape (mineral tundra) was a weak sink for atmospheric methane. Vascular plant cover was a key factor in explaining the spatial variability of CH 4 emissions among wetland types, as indicated by the positive correlation of emissions with the leaf area index (LAI). As elucidated through a stable isotope analysis, the dominant CH 4 release pathway from wetlands to the atmosphere was plantmediated diffusion through aerenchyma, a process that discriminates against 13 C-CH 4 . The CH 4 released to the atmosphere was lighter than that in the surface porewater, and δ 13 C in the emitted CH 4 correlated negatively with the vascular plant cover (LAI). The mean value of δ 13 C obtained here for the emitted CH 4 , −68.2 ± 2.0 ‰, is within the range of values from other wetlands, thus reinforcing the use of inverse modelling tools to better constrain the CH 4 budget. Based on the IPCC A1B emission scenario, a temperature increase of 6.1 • C relative to the present day has been predicted for the European Russian tundra by the end of the 21st Century. A regional warming of this magnitude will have profound effects on the permafrost distribution leading to considerable changes in the regional landscape with a potential for an increase in the areal extent of CH 4 -emitting wet surfaces.

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Section: Discussionmentioning

confidence: 99%

Methane dynamics in the subarctic tundra: combining stable isotope analyses, plot- and ecosystem-scale flux measurements

et al. 2016

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“…Dlugokencky et al, 1994), (b) decreases in anthropogenic emissions before 1999, and decreases in wetland emissions after that (Bousquet et al, 2006) or (c) changes in the removal rate by OH (e.g. Monteil et al, 2011). A network of eddy covariance (EC) towers can provide direct and continuous monitoring of ecosystem scale surface fluxes that can be upscaled to landscape and continental scales using process-based models.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the performance of commonly used gas analysers for methane eddy covariance flux measurements: the InGOS inter-comparison field experiment

et al. 2014

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Abstract. The performance of eight fast-response methane (CH 4 ) gas analysers suitable for eddy covariance flux measurements were tested at a grassland site near the Cabauw tall tower (Netherlands) during June 2012. The instruments were positioned close to each other in order to minimise the effect of varying turbulent conditions. The moderate CH 4 fluxes observed at the location, of the order of 25 nmol m −2 s −1 , provided a suitable signal for testing the instruments' performance.Generally, all analysers tested were able to quantify the concentration fluctuations at the frequency range relevant for turbulent exchange and were able to deliver high-quality data. The tested cavity ringdown spectrometer (CRDS) instruments from Picarro, models G2311-f and G1301-f, were superior to other CH 4 analysers with respect to instrumental noise. As an open-path instrument susceptible to the effects of rain, the LI-COR LI-7700 achieved lower data coverage and also required larger density corrections; however, the system is especially useful for remote sites that are restricted in power availability. In this study the open-path LI-7700 results were compromised due to a data acquisition problem in our data-logging setup. Some of the older closed-path analysers tested do not measure H 2 O concentrations alongside CH 4 (i.e. FMA1 and DLT-100 by Los Gatos Research) and this complicates data processing since the required corrections for dilution and spectroscopic interactions have to be based on external information. To overcome this issue, we used H 2 O mole fractions measured by other gas analysers, adjusted them with different methods and then applied them to correct the CH 4 fluxes. Following this procedure we estimated a bias of the order of 0.1 g (CH 4 ) m −2 (8 % of the measured mean flux) in the processed and corrected CH 4 fluxes on a monthly scale due to missing H 2 O concentration measurements. Finally, cumulative CH 4 fluxes over 14 days from three closed-path gas analysers, G2311-f (Picarro Inc.), FGGA (Los Gatos Research) and FMA2 (Los Gatos Research), which were measuring H 2 O concentrations in addition to CH 4 , agreed within 3 % (355-367 mg (CH 4 ) m −2 ) and were not clearly different from each other, whereas the other instruments derived total fluxes which showed small but distinct differences (±10 %, 330-399 mg (CH 4 ) m −2 ).Published by Copernicus Publications on behalf of the European Geosciences Union. 3164O. Peltola et al.: Evaluating the performance of gas analysers for CH 4 EC flux measurements

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“…Incorporating δ 13 C-CH 4 and δD-CH 4 data sets in chemistry transport models is useful for quantitatively separating different CH 4 source categories and attempts have been made to reduce uncertainties in the global CH 4 budget (e.g. Hein et al, 1997;Mikaloff Fletcher et al, 2004a, b;Monteil et al, 2011;Kirschke et al, 2013;Ghosh et al, 2015;Rice et al, 2016;Schaefer et al, 2016;Schwietzke et al, 2016;Röckmann et al, 2016;Turner et al, 2017;Rigby et al, 2017). However, although an increasing number of δ 13 C-CH 4 and δD-CH 4 data have been reported over the last decades, significant measurement offsets among laboratories have been found for both δ 13 C-CH 4 (e.g.…”

Section: Introductionmentioning

confidence: 99%

Interlaboratory comparison of δ13C and δD measurements of atmospheric CH4 for combined use of data sets from different laboratories

et al. 2018

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Abstract. We report results from a worldwide interlaboratory comparison of samples among laboratories that measure (or measured) stable carbon and hydrogen isotope ratios of atmospheric CH 4 (δ 13 C-CH 4 and δD-CH 4 ). The offsets among the laboratories are larger than the measurement reproducibility of individual laboratories. To disentangle plausible measurement offsets, we evaluated and critically assessed a large number of intercomparison results, some of which have been documented previously in the literature. The results indicate significant offsets of δ 13 C-CH 4 and δD-CH 4 measurements among data sets reported from different laboratories; the differences among laboratories at modern atmospheric CH 4 level spread over ranges of 0.5 ‰ for δ 13 C-CH 4 and 13 ‰ for δD-CH 4 . The intercomparison results summarized in this study may be of help in future attempts to harmonize δ 13 C-CH 4 and δD-CH 4 data sets fromPublished by Copernicus Publications on behalf of the European Geosciences Union. 1208T. Umezawa et al.: Interlaboratory comparison of δ 13 C and δD measurements of CH 4 different laboratories in order to jointly incorporate them into modelling studies. However, establishing a merged data set, which includes δ 13 C-CH 4 and δD-CH 4 data from multiple laboratories with desirable compatibility, is still challenging due to differences among laboratories in instrument settings, correction methods, traceability to reference materials and long-term data management. Further efforts are needed to identify causes of the interlaboratory measurement offsets and to decrease those to move towards the best use of available δ 13 C-CH 4 and δD-CH 4 data sets.

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Interpreting methane variations in the past two decades using measurements of CH<sub>4</sub> mixing ratio and isotopic composition

Cited by 107 publications

References 53 publications

Methane dynamics in the subarctic tundra: combining stable isotope analyses, plot- and ecosystem-scale flux measurements

Methane dynamics in the subarctic tundra: combining stable isotope analyses, plot- and ecosystem-scale flux measurements

Evaluating the performance of commonly used gas analysers for methane eddy covariance flux measurements: the InGOS inter-comparison field experiment

Interlaboratory comparison of <i>δ</i><sup>13</sup>C and <i>δ</i>D measurements of atmospheric CH<sub>4</sub> for combined use of data sets from different laboratories

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Interpreting methane variations in the past two decades using measurements of CH&lt;sub&gt;4&lt;/sub&gt; mixing ratio and isotopic composition

Cited by 107 publications

References 53 publications

Methane dynamics in the subarctic tundra: combining stable isotope analyses, plot- and ecosystem-scale flux measurements

Methane dynamics in the subarctic tundra: combining stable isotope analyses, plot- and ecosystem-scale flux measurements

Evaluating the performance of commonly used gas analysers for methane eddy covariance flux measurements: the InGOS inter-comparison field experiment

Interlaboratory comparison of &lt;i&gt;δ&lt;/i&gt;&lt;sup&gt;13&lt;/sup&gt;C and &lt;i&gt;δ&lt;/i&gt;D measurements of atmospheric CH&lt;sub&gt;4&lt;/sub&gt; for combined use of data sets from different laboratories

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Interpreting methane variations in the past two decades using measurements of CH<sub>4</sub> mixing ratio and isotopic composition

Interlaboratory comparison of <i>δ</i><sup>13</sup>C and <i>δ</i>D measurements of atmospheric CH<sub>4</sub> for combined use of data sets from different laboratories